GB1436941A - Gyroscopic apparatus - Google Patents

Abstract

1436941 Caging mechanism for gyroscopes SPERRY RAND Ltd 14 May 1973 [12 May 1972] 22475/72 Heading G1C Gyroscopic apparatus comprises at least one two-degree-of-freedom gyroscope 1, 2 each having a sensitive element mounted in an inner gimbal rotatable about an axis 4, 5, an outer gimbal mounted about an axis 6, 7 orthogonal to the inner gimbal axis 4, 5 and a caging mechanism 8, for effecting simultaneous caging of the inner and outer gimbals, which comprises a plunger 35 releasably operable to engage a recess 62 on a member 63 on the inner gimbal axis 4, 5. The line of action of the plunger 35 passes through the inner gimbal axis 4, 5 and is parallel to the outer gimbal axis 6, 7 so that no precessional torques are applied to the gyroscope when mechanism 8 is disengaged. The plunger 35 is in the form of a slide mounted in a housing, on springs which are compressed in the caged position, for movement relative thereto, the movement being effected through a cam follower 32 by a cam. In the embodiment described, two gyroscopes 1, 2 are employed, the inner gimbal axes 4, 5 being coaxial, the outer gimbal axes 6, 7 being orthogonal thereby allowing three axis data to be generated. Two caging mechanisms 8 at right angles to each other are then employed, the cams being in the form of parallel connected wheels 19, 24, one wheel 19 comprising a worm wheel driven via a worm gear 18 by a single stepper motor 11. Thus when the gyroscopes 1, 2 are to be caged, they are torqued to within, preferably 1 degree of the caged positions of the gimbals. Mechanism 8 is then actuated by driving motor 11, the wheels 19, 24 rotating so that the respective cam followers 32 begin to follow constant rise portions in cam tracks 25, 26, the plungers 35 moving until they engage the respective recesses 63. Uncaging requires the followers 32 to overcome a step in the cam track, the springs in the plunger 35 then snapping the plungers 35 back to their caged position. A limit switch may be incorporated in the mechanism 8 so as to indicate when the gyroscopes 1, 2 are caged and uncaged.